The natural-gas surcharge for UniSource Energy Systems customers was extended by the Arizona Corporation Commission on Friday.
The commission voted to extend the surcharge of 11.5 cents per therm until the $7.1 million is collected.
Citizens Arizona Electric, which recently was purchased by UniSource, began collecting the $38 million surcharge in the fall of 2001 to recover increased wholesale cost of natural gas from the previous winter that had not been recovered from retail customers.
The commission declared a surcharge holiday last winter that would have left $7.1 million uncollected by the end of October.
The surcharge was not addressed by the commission ruling that approved the purchase of Citizens by UniSource.
The commission Friday included a circuit-breaker clause for customers.
No one will have to pay for more than140 percent of the average therms used by all gas customers in Northern Arizona.
Commission spokesperson Heather Murphy said an average would be calculated for each of the 12 months to set the maximum and would be the same for all residential gas customers.
Continuing wholesale price increases for natural gas and a base-rate increase of more than 20 percent approved by the commission in July have pushed the per-therm rate for residential customers to 89 cents without the 11.5 cent surcharge, UniSource customer relations director Steve Lynn said.
Mohave County residents could pay more than $1 per them for natural gas this winter with the reinstatement of the 11.5-cent surcharge.
The rate charged gas users starts with a $7 customer service fee, up from $5 before the sale to UniSource.
A base rate per therm amounts to about 14 cents.
A variable rate per therm, now at 75 cents, is a rolling average based on what UniSource must pay for natural gas.
"That variable rate prevents spikes in prices and changes the customer charge as natural gas prices move up and down," Lynn said.
"It is the responsibility of UniSource to make long range contracts for gas that will keep the price stable."
The rolling average based on what UniSource pays for natural gas each month.
If gas supplies are short and winter is colder than normal, prices could go up as much as 10 cents per therm in a single month.
Such increases require no ACC approval.
Customers concerned about large gas bills this winter can call UniSource and change to budget billing, which can level heating costs over the next 12 months.
UniSource has a program for qualified low-income natural gas and electricity users that will assist them with bills.
Customers are qualified through application to the state Department of Economic Security.
Call UniSource in Kingman or (800) 635-8033 for information.
Applications are available in UniSource offices in Kingman.